Intelligent wells are about timely information and response. Designed to obtain real-time downhole data to gain critical wellbore and reservoir information, they are likewise equipped with the well completion and control technology to enable swift, responsive actions that minimize asset risk and optimize production.

According to recently published industry data, the number of intelligent well systems around the world is projected to grow from roughly 150 last year to 660 during the next 3 years. While the absolute numbers are still small, the growth rate indicates rapid expansion and possibly a tipping point passed on the way to widespread application of this technology.

"Intelligent well technology is regarded as mainstream in today's well design activities," said Doug Meikle, Halliburton Energy Services Group vice president for the Landmark and Project Management product service line. "Focusing on both reliability and a range of fit-for-purpose solutions has resulted in expansive installation growth over the last few years. Today's technology largely comprises a rugged set of hydraulically actuated multi-position (choking) downhole control valves, of which several are typically run per well to manage different intervals or zones. Intelligent well product options now span everything from tertiary recovery land fields to the most challenging offshore deepwater high-pressure/high-temperature (HP/HT) environments."

The target of much current product development activities is to produce a new suite of "digital infrastructure" or surface controls and automation systems that create an essential real-time link into the intelligent operations domain, Meikle said.

"These surface systems provide options for making data available to wider Scada systems and for enabling real-time control," he said. "Looking ahead, development activities are investigating cableless systems where control modules might be installed in lateral branches, gravel packs or openhole environments. These technologies open the possibility of retrofit installations - without pulling or running tubing - thus increasing the applicable market.

"The importance of this suite of technologies ranges from reducing intervention through production optimization to increasing ultimate recovery of reserves. In today's maturing oilfield market, this technology set is one of a growing range of tools for improving management of the world's energy assets."

Joe Vandeiver, president of the recently formed Production Optimization business unit at Baker Hughes, said, "As the application of wellbore monitoring technology becomes more and more commonplace, the focus expands to the development and application of intelligent production systems. Through monitoring and controls, intelligence in the production equipment is linked with the various components such as intelligent artificial lift and chemical flow assurance, if they are present. What you get is an intelligent well bore that senses the dynamics of the completion as well as the whole production system. And in addition to monitoring for reservoir issues, the monitoring system can continuously check the condition of the completion and the production equipment. You can lose production not only because of suboptimal alignment of the well with the reservoir, but also due to failures in the completion and production equipment."

However, regardless of how sophisticated the response mechanism of the well system is, just having the needed information on a timely basis can be

the critical factor.

"Some time ago in South America, we installed an intelligent well system controlling several zones," Vandeiver said. "The customer later told us that results in the well were proving disappointing, as incremental production had not been up to expectations. We went out to investigate and found that the customer had changed the valve position on the well, but the operations people had not thought to change the speed of the electric submersible pump (ESP). The well was ready to give up more, but the pump wasn't. So a simple service call to speed up the pump produced an incremental 300 b/d of oil.

"The customer was happy, but everyone would have been happier had the production system been able to tell the customer on the spot that 'you changed the valve opening and pump intake pressure, and therefore you need to speed up the pump.' The pump adjustment is something that we could have done remotely, or the customer manually. But the customer in any case would have known right away. That's the kind of system we can now provide, and its value is evident."

Multizone intelligent completions enable various options for flowing a well to optimize production, said David Walker, Completion Systems product line manager for BJ Services, which provides remotely controllable zonal isolation and flow control systems for intelligent completions.

"Say you have two zones - you can commingle production from them if they're closely enough pressured and have similar characteristics," Walker said. "This results in a greater production rate and quicker payout. Where that is not possible, you can produce one zone while closing off the other and periodically alternate between them to maximize daily rates and your return on investment. Where water cut is getting excessive, you can shut off production from that zone and produce from the other until the water table stabilizes, then go back to producing the first zone. Intelligent completions are also seeing increasing use in long, exposed horizontal sections where production in some zones might be lost if intervals in front of them water out. With the ability to choke off a threatened zone, you can reduce water cut in the well and return to producing that section when water coning is no longer a threat.

"The ability to execute your flow-control options remotely, which is an integral part of all intelligent completions we perform, enables the fastest response to downhole information."

For Weatherford, which provides full intelligent completion offerings that include sensing, flow-control and remote operability options, a major focus is its optical sensor products for permanently monitoring pressure, temperature, distributed temperature and flow.

"Optical sensors are well suited for reliable, stable, life-of-well monitoring for all environments," said Tad Bostick, vice president, Intelligent Completions Business Development, Weatherford. "This includes the more hostile environments such as high temperature and pressure and high shock and vibration as well as complex, multiparameter monitoring requirements and high-risk situations such as subsea. In that case, wells are usually high-cost and interventions very expensive, so they must be avoided." Weatherford also provides electronic sensor products, which are appropriate for lower-temperature and less hostile environments.

"Sometimes there's no real alternative to using optical sensors for obtaining the needed measurements," said Tor Kragas, Production Applications product line manager, Weatherford. "One example is continuous temperature measurements across the sandface, whether across multiple reservoirs in a multizone intelligent completion or along a long lateral section in one reservoir. By installing a fiber-optic cable along the wellbore length, you can actually make temperature measurements at every meter. Depending on flow conditions and other available measurements, it may be possible to infer flow distribution from the data as well."

Downhole optical multiphase flow meters, another Weatherford product, provide an alternative to metering methods that restrict flow path in the production tubing, such as Venturi devices.

"When flow path is restricted, you don't have full-bore access beyond the meter," Kragas said. "With the optical flowmeter, the flow sensors are on the outside of the production tubing. This fullbore access is particularly important with intelligent completions, where operators may wish to install devices or perform operations below the meter."

The company's Clarion optical seismic sensing system for permanent in-well monitoring is an innovative product recently commercialized.

"These tubing- or casing-conveyed devices enable you to collect time-lapse borehole seismic images beyond the wellbore area, out into the reservoir," Bostick said. "The sensors are multicomponent seismic devices that can also continuously monitor the potential dynamics in the reservoir that excite microseismicity, such as fracturing caused by subsidence, stimulation, injection or production. These stress changes can be occurring above, within or below the reservoir, and this information can be extremely important to assessing the overall impact of subsurface production activities in a field.

"The permanent in-well sensors can also capture seismic information in conjunction with 4-D surface seismic surveys to help calibrate and better understand this data."

At Shell Exploration & Production, initial involvement with intelligent completions led to the company's initiative with intelligent fields, said Pieter Kapteijn, Smart Fields Program manager.

"The smart-well technology very early on was seen as a novel way of completing wells, and we very soon found that the application of smart wells not only improves the value and functionality

of the individual wells but actually spins off functionality and data that can be used on a field level," he said. "So we migrated from a very narrow view of smartness based around the well to a more broad view of smartness based around the asset. For us, smartness means that you can now sense and control at reservoir level and make very complex well architectures almost work like individual wells. It becomes an active sensor into your reservoir, but it also becomes an active control element in your reservoir management strategy.

"To give an example, recently we completed what we call a snake well in Brunei, which is a very complex well that meanders through multiple zones for 3 km [about 2 miles]. Just running it as a conventional well and commingling all that production would probably result in very disappointing performance. The drawdown wouldn't be right, and you would be pulling gas or water. But with a smart well, you can actually get this well to act as five or six individually controlled and optimized drainage points. The success has been remarkable. A well such as this is a lot cheaper than drilling individual wells for those reservoirs. The ability to do this has an impact on the number of wells you drill and the footprint of the size of your platforms and wells. So smart wells start to optimize other decisions around your asset as well."

The spread of intelligent wells primarily has been driven by two factors, one the technology and the other a purely operational issue, said Satish Pai, vice president, Technologies, Oilfield Services, Schlumberger.

"From a technology standpoint, reliability is absolutely critical for permanently installed well components," Pai said. "Years ago, if you put in something like a permanent gauge, too often it would fail. The cost of pulling it out and replacing it was quite large. However, the reliability of intelligent devices placed down the well has improved so much that operators now have high confidence in them. Consequently, their use is rapidly spreading from offshore to onshore wells. This is good because receiving downhole data as a well is being produced, which is the core benefit of intelligent completions, allows you to do proactive reservoir management. Thus, before a well gets into trouble, you can take effective steps and improve recovery.

"From an operational perspective, the big discoveries have been in deep water and are being developed with subsea completions. The cost of later interventions in these wells is quite high. The general practice with deepwater subsea completions is to instrument the well with fiber optics across the sandface, permanent pressure gauges and flow control valves, and have those controlled from shore. This is a proactive measure that enables you to get data that you can act upon before something goes wrong, thus avoiding the need to take a rig back on well site to intervene. These intelligent completions on subsea wells seem to be exponentially taking off - in West Africa, the North Sea and even Asia. Subsea projects will demand these well designs because the potential need for interventions with conventional wells is too big a cost risk."